This works good on the PC76XL also, just as Nomad posted.
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Cobra 29LTD Chrome VFO windup...
- Thread starter CorruptHawkeyez
- Start date
I like this mod and have used it myself. Just be a good neighbor and understand that your carrier sweeps across the channel below you each time you transmit.
Correction: The channel above you...
Correction: The channel above you...
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It's very simple for the Cobra 29. Attach the positive leg of a 47uf electrolytic cap (for quick windup) or a 100uf electrolytic cap (longer windup) to the banded end of D18. Attach the negative leg to the can adjacent to D18. A switch can be installed in series with the negative leg if needed.
The radio will need to be realigned for correct TX "resting" frequency. Attach a frequency counter and key the radio for about 5 seconds to allow the TX frequency to "level out". Then adjust the TX frequency while keeping the radio keyed.
Just remember that this mod will only be heard in the heterodyne on the receiving end when you key up with another station. It will not be heard on your end or if there is no one else keying with you at the same time. You can however hear the windup on a SSB radio set to LSB if you want to hear how slow or fast your windup speed is.
The radio will need to be realigned for correct TX "resting" frequency. Attach a frequency counter and key the radio for about 5 seconds to allow the TX frequency to "level out". Then adjust the TX frequency while keeping the radio keyed.
Just remember that this mod will only be heard in the heterodyne on the receiving end when you key up with another station. It will not be heard on your end or if there is no one else keying with you at the same time. You can however hear the windup on a SSB radio set to LSB if you want to hear how slow or fast your windup speed is.
Sure would be annoying if it did this in sideband modes. For that matter sideband is pretty annoying to use unless the clarifier keeps the transmit and receiver frequency each 'locked' together.
Might want to have a way to switch it off for sideband, and back on for AM.
Only place I've seen this mod is in AM-only models. The front-panel clarifier knob never gets connected to the transmit side in this kind of CB.
And if you only used your Washington on AM, it wouldn't matter if this messed up sideband modes.
73
Isnt that how it always is ? Always the followers trying to impress the head rich dummie who has all the latest and greatest
If I'm remembering correctly, there is no "fine tune" or "delta tune" on this model.
And that's the circuit feature that is being hijacked to accomplish this mod.
A radio that doesn't have that knob will be an uphill struggle to design and install to get the key-down windup.
And the wider the frequency up/down range is on that knob, the wider the windup will be on transmit.
73
And that's the circuit feature that is being hijacked to accomplish this mod.
A radio that doesn't have that knob will be an uphill struggle to design and install to get the key-down windup.
And the wider the frequency up/down range is on that knob, the wider the windup will be on transmit.
73
No it's more to do with the value of the capacitor that effects the length of the frequency offset. The resistor is more for bleed off after you unkey. That way you don't have to wait for the cap to discharge before you can key again and actually get your effect